Back, now, at 7:41, with safety concerns about aging car tires and whether they can cause fatal accidents. ABC's Brian Ross has news this morning about a new investigation into tire safety and about what you need to look for that could save your life. Brian? Reporter: Well, good morning, Lara. The national transportation safety board has launched a first of its kind special investigation into the role of tires in hundreds of traffic accident deaths a year. And among the issues, tires that look perfectly safe, even brand-new. But that automakers say can begin to degrade and should be replaced just six years after they were made. There was just a terrible accident on I-10. Reporter: The tire that failed in this accident was ten years old. Someone lost control of their vehicle and flew into the right shoulder. Reporter: The tire that failed in this accident outside of Los Angeles, was eight years old. My daughter lost her life because of it. My grandson is growing up without his mother. Reporter: And the tire that failed in this fatal accident in Louisiana was ten years old. And helped lead the new federal investigation by the safety board, the ntsb. It's a significant issue. That's why we're looking at it at the ntsb. Reporter: Safety engineers saying depending on how they're maintained and where they're used, tires can age and lose elasticity after six years. The tread can begin to separate, even though the tires may never have been on the road and appear to be perfectly new. That's what's so troubling. It really is the invisible hazard. Reporter: But no current law or industry standard prevents the sale of aged tires. Our investigation with ABC stations around the country, found plenty of them for sale, described as perfectly safe. In New York, 8 1/2-year-old tires. Out with the old. In with the new. You know that expression? Reporter: In Rhode Island, 9-year-old tires. In San Francisco, 11-year-old and 15-year-old tires. Ford, gm and Chrysler, all recommend that tires more than six years old be replaced, regardless of how much they've been used. But the government and the tire industry say, there's no reason to have a tire aging standard of any kind. Wouldn't that help safety, given the recommendations of Ford, gm and Chrysler? We disagree. Reporter: It wouldn't help safety? It would not. There's no data to support expiration dates. Reporter: One of the biggest tire companies, Michelin, recommends a ten-year replacement date. For consumers to know how old the tires are, they have to decode the method of lifting the production date. The last four digits give the date. Not by month and year, but by week and year. That's the code for the 13th week of 2003. It's convenient for the consumer. Reporter: To do it by the week? Certainly it is. Reporter: Are you purposely hiding how old the tires are? We're not hiding that in the least. Reporter: And thanks to the lobbying of the tire industry, proposals of eight states to have tire age, have been defeated. Show us again. At the very end of this, and right here, it says 4105. 4105 is the 41st week of 2005, October 2005. But you have to know the code. You have to decode it to understand. The week and the month. For the tire industry, it's better for them. Better for them. Not so great for the consumer, who has to really figure out how to read this. Now, we know. Thanks to you. You can hear more of Brian's report on tire safety. That's tonight on "World news" and also on "Nightline." And we posted a video on our website showing you step-by-step, how to check the age of your tires. Go to goodmorningamerica.com on Yahoo! To check it out.

This transcript has been automatically generated and may not be 100% accurate.

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